coll/han: set as default except if processes are consecutive across nodes

[devreal]

coll/han provides better latency than coll/tuned in cases where processes are mapped to nodes nonconsecutively, e.g., using --rank-by node. In that case coll/han reduces the amount of cross-node traffic. Its benefits are less clear with linear consecutive process placements. We try to detect linear process placement and if found reduce the priority of coll/han to below coll/tuned. A new mca parameter coll_han_priority_penalty is used to control the adjustment (10 by default).

This PR addresses https://github.com/open-mpi/ompi/issues/10347 for coll/han by increasing the default priority of coll/han to 35 (coll/tuned stands at 30)

Signed-off-by: Joseph Schuchart [email protected]